DCS allows for efficient monitoring, control and management of the production process by distributing controllers to specific areas or devices. So how does DCS work? Let's explore the details in the article below.

1. What is a DCS system?

DCS (Distributed Control System) is a distributed control system commonly used in manufacturing plants and automated industrial processes. DCS distributes controllers to each separate area or device in the entire system, helping to optimize monitoring and control.

DCS systems are used to manage complex, continuous and highly accurate production processes such as: oil and gas, chemicals, electricity, food, pharmaceuticals, etc.

2. Classification of DCS distributed control systems

DCS distributed control systems are divided into three main types, depending on the platform and control architecture used. Each type of DCS system has its own advantages, suitable for each scale and operating characteristics of the enterprise.

Traditional DCS system

This is a type of DCS system developed according to the architecture of each manufacturer. These systems often need to combine PLC (Programmable Logic Controller) to undertake more complex control tasks.

PLC-based DCS system

Modern PLC lines not only process simple logic but also have the ability to work with analog signals, perform arithmetic operations and feedback control algorithms. In PLC-based DCS systems, the control device is often configured strongly, supporting sequential programming and advanced control methods, helping to improve flexibility and efficiency in production process management.

PC-based DCS system

PC-based DCS systems have outstanding advantages in terms of free programming ability, high computing performance and flexible expansion. In addition, competitive price and multi-functional integration capabilities are also factors that make this type of system popular in applications requiring large data processing or user-friendly interfaces.

3. What is the function of the DCS system?

The DCS (Distributed Control System) plays a core role in automating and monitoring the entire technological process in the factory. DCS also takes on the role of operating and monitoring the system, helping businesses optimize performance, ensure safety and maintain stable quality.

Control in the DCS system

Depending on the characteristics of the production process, the control function is divided into two main forms:

Automatic adjustment: DCS takes on the task of automatically responding and adjusting loops in the continuous production process, ensuring that technological parameters are always maintained within allowable limits.
Sequential control: DCS coordinates the operating steps in a sequence of events, suitable for processes that require clear sequences such as packaging, mixing, feeding, etc.

System operation and monitoring

DCS is capable of displaying the entire production process on the operating screen in an intuitive and easy-to-observe manner. Parameters and equipment status are presented in a variety of ways through intuitive graphical interfaces, charts, data tables, and intelligent warning systems:

Intelligent warning system, including multiple levels:

• Risk warning (Warning)
• Alarm (Alarm)
• Failure

4. What are the components of a DCS system?

The DCS (Distributed Control System) is made up of many different components, which perform the functions of control, monitoring, configuration and communication throughout the entire system. Below are the main components of a DCS system:

Local Control Unit (LCU)

The local control station, also known as the process station (PS), is where the main control tasks for each production stage are performed, helping to process data from field devices, calculate and send appropriate control signals.

Operator Station (OS)

This is where the operator monitors and controls the entire process through an intuitive graphical interface. The operator station is usually located in the central control room, but can also be distributed in each workshop to conveniently monitor each part of the production line. OS stations can operate in parallel and independently.

Engineering Station (ES)

The engineering station is used to configure the system, install software, parameterize field devices, write and edit control programs, create human-machine interfaces (HMI) and monitor the operation of the entire system.

Communication system

The communication system in DCS includes:

System Bus (system bus): Connects control stations, operating stations and engineering stations together, forming a unified control network.

Fieldbus (field bus): Connects the control station with distributed I/Os and smart field devices such as sensors, control valves, etc.

The communication system is a key factor in helping to exchange data quickly and accurately between components in the system.

Other extended components

In addition to the main components, the DCS system can also include: Remote I/O Station, dedicated controller, etc.

5. Programming steps for a standard DCS system

Programming for a distributed control system (DCS) is an in-depth process, including many steps of coordination between hardware, software and communication technology. Below are the basic programming steps in a DCS system:

Setting up the DCS system

The DCS system is configured based on a DCS server (DCS Server) and many engineering stations (Engineering Workstations). The entire system from hardware, software to communication platform is often provided synchronously from a single manufacturer, ensuring high compatibility and synchronization.

Create an integrated programming project

Programming engineers will build an integrated project, which includes:

• PLC control program - logic processing and device control.
• SCADA program - serving real-time data display and monitoring.

These two parts are closely linked to synchronize the system control and operation process.

DCS Project Implementation

After completing the programming, the system is deployed through the following steps:

• Download the control program to the PLC
• Launch the SCADA program on the operating computers
• Configure and download the program for the Remote I/O devices and field devices
• This process helps the system to operate stably and accurately according to the design parameters.

Editing and maintenance during operation

While the system is operating, the engineer can make technical edits if granted access to the system. If he wants to change the operation of a pump in SCADA, the engineer can click on the pump icon, the corresponding control program from the PLC will be uploaded and displayed directly on the computer screen for editing.

6. What are the advantages of the DCS system?

The DCS (Distributed Control System) is not only the optimal solution in modern manufacturing plants but also brings many outstanding advantages in terms of flexibility, operational efficiency and system control. Below are the outstanding advantages of the DCS system:

High and comprehensive control level

DCS is a control system that integrates processors, communication networks and operating software. Thanks to that, the system can manage thousands of input/output (I/O) points and control many complex processes accurately and efficiently used in large-scale industries such as chemicals, oil and gas, energy, etc.

Flexible configuration and easy to expand

The DCS system is designed with a redundant architecture in all components. Allows users to change programs, add or remove modules in the system structure without stopping the machine or restarting the entire process. In addition, DCS also supports many popular communication protocols such as Profibus, Ethernet, Foundation Fieldbus, ensuring connectivity from field level to management level.

Minimize errors and save operating costs

DCS has the ability to flexibly integrate with PLC systems, ensuring effective control of separate stages in the production line. With an open system and high automation capabilities, DCS helps to significantly reduce error rates, while saving operating and maintenance costs for businesses.

High reliability and availability

One of the most outstanding advantages of the DCS system is its ability to operate stably and continuously. The system is integrated with the following features:

• Automatic error prevention
• Real-time problem diagnosis
• Display warnings and detailed error reports
• Options to set up system access and security

7. Distinguishing between DCS and SCADA

DCS (Distributed Control System) and SCADA (Supervisory Control and Data Acquisition) are both popular control systems in the industrial sector. Below is a comparison table between DCS and SCADA:

With flexible control, high precision and outstanding stability, the DCS system is suitable for continuous production processes that require high reliability and quick response. Meanwhile, SCADA is the optimal choice for systems with wide geographical distribution, requiring remote monitoring of many different points. For more information, please contact Intech Group via hotline 0966.966.103 / 0966 966 032 for timely advice and support.